This invention relates to a network management system for managing the entirety of a network via a network element management system which manages a large number of network elements of a wide variety using managed objects. More particularly, the invention relates to a network management system, which is connected to one or a plurality of network element management systems each connected to one or more network elements, for performing network management via these network element management systems.
There is available a network management system for managing the entirety of a network via a network element management system which manages a large number of network elements of a wide variety using managed objects.
According to the prior art, such a network management system has a manager-agent architecture stipulated by the ISO and manages network elements or networks while transmitting handling directives to managed objects in the network element management system using a prescribed management protocol, e.g., a CMIP (Common Management Information Protocol).
FIG. 7 is a diagram useful in describing a system management model and illustrates the relationship among manager-agent architecture, CMIP and managed objects MO. A manager M manipulates or controls the managed objects MO, which are managed by a management information database (MIB) within an agent A.
Using an object-oriented technique, the managed object MO model network resources RSC constituting a network. Examples of the resources are lines, multiplexer/demultiplexers and virtual communication paths. Variables representing various states (attributes) possessed by each of the network resources RSC are referred to as attribute information possessed by the managed objects. Network management refers to the manipulation of the managed objects MO and the manipulations include:
(1) creating managed objects (M-CREATE);
(2) deleting managed objects (M-DELETE);
(3) reading out attributes of managed objects (attribute acquisition) (M-GET);
(4) setting or changing attributes of managed objects (M-SET);
(5) executing functions possessed by the managed objects (M-ACTION); and
(6) receiving event notification from managed objects (M-EVENT-REPORT).
The manager M is a mechanism for performing the core functions that implement network management. The manager M does not control the managed objects directly but rather it is the agent A that controls the managed objects. To accomplish this, the manager M sends handling directives to the agent A using the management protocol CMIP, thereby controlling the managed objects indirectly to perform network management. This management operation makes it possible to manipulate a plurality of managed objects MO simultaneously by a single management operation.
FIG. 8 is an explanatory view showing the concept of a basic network hierarchy in network management. In a TMN (Telecommunication Management Network) stipulated by the 3000 Series of ITU-TM Recommendations, network management functions are classified into the following four layers to clarify them:
(1) an element management layer EML;
(2) a network management layer NML;
(3) a service management layer SML; and
(4) a business management layer BML (not shown).
Network element management systems (EML-OS) 11, 12 are connected to one or a plurality of network elements (NE) 1.about.4 and control managed objects to thereby managed each network element. A network management system (NML-OS) 21 is connected to one or a plurality of network element management systems 11, 12 and manages the network elements of the overall network via these network element management systems. More specifically, the network management system 21 manages network information such as the network element management systems 11, 12 that manage the network elements, the individual management domains (network elements) of these network element management systems and the communication paths connecting these domains.
A service management system (SML-OS) 31, which is connected to the network management system 21, requests the network management system 21 for prescribed network information in accordance with a directive from a user interface (user terminal) 32, receives this network information and then outputs the same. Further, a user terminal 22 requests the network management system 21 for prescribed network information directly, receives this information and either displays the information on a display unit or prints out the information by means of a printer.
FIG. 9 is a diagram useful in describing the relationships between systems. FIG. 9 shows the relationships between the systems of FIG. 8 taking into consideration the manager-agent architecture of FIG. 7. Shown in FIG. 9 are agents A, managed objects MO, applications APL and management information databases MIB. Higher and lower layers have a manager--agent relationship and communicate via the management protocol CMIP.
The network management system 21 functions as an agent A for storing managed objects MO, which are for managing the network information connecting the network element domains, in the management information database MIB, and supplying the service management system 31 with the network information. Further, the network management system 21 acts as the manager M of the network element management systems 11, 12 and performs network management by manipulating managed objects MO (obtained by modeling each of the network elements), which have been stored in the management information database MIB, via the agent function of the network element management systems 11, 12. Further, the network management system 21 makes it possible to specify network information manipulation directly from a user terminal via a user interface function.
The network element management systems 11, 12 function as agents A for storing managed objects MO, which are for managing network information such as the network elements connected to these systems 11, 12 and the lines connecting these network elements, in the management information database MIB, and supplying the network management system 21 of the higher layer with the network information. Further, the network element management systems 11, 12 act as managers of the network elements 1, 2 and perform network management within limits specified by manipulating managed objects MO, which have been stored in the management information database MIB, via the agent function of the network elements 1, 2.
FIG. 10 is a diagram useful in describing problems encountered with conventional network management. Each of the network element management systems 11, 12 has a communication controller CMN for implementing control of communication with the network management system 21, which is the higher layer, the management information database MIB for storing managed objects MO, and an behavior execution controller BEC for controlling prescribed managed objects MO. The behavior execution controller BEC performs network control by (1) controlling managed objects MO in accordance with handling directives from the network management system 21 or (2) controlling managed objects MO autonomously. The network management system 21 has a scenario controller SRC. When a network information acquisition request or modification request or some other network management request is entered from the user terminal 22 or service management system 31, the scenario controller SRC outputs a series of handling directives, which are required to implement these requests, as a scenario. The network management system 21 further includes the communication controller CMN for controlling communication with the network element management systems 11, 12 of the lower layer.
There are cases where the network management system 21 executes processing to modify network information in response to a request from the service management system 31 or user terminal 22. Upon being requested to execute such processing for modifying network information, the network management system 21 must transmit handling directives (1).about.(4) for a plurality of managed objects to the plurality of network element management systems 11, 12. To accomplish this, the network management system 21 handles the handling directives for the plurality of managed objects as a single scenario, repeatedly transmits the handling directives to each of the network element management systems 11, 12 in numerical order and verifies the result of the response to the handling directives to thereby modify the network information.
However, when a handling directive fails in the midst of a scenario, i.e., when a response to manipulation is erroneous for some reason, the service management system 31 or user terminal 22 must be notified of the fact that execution of the network information modification processing ended abnormally. In addition, it becomes necessary to execute processing ("rollback" processing) for returning the attribute value of each managed object to the value that prevailed prior to the modification. Rollback processing is carried out by (1) executing attribute value acquisition processing (M-GET) before executing processing (M-SET) for setting an attribute value, (2) executing processing for setting the attribute value under conditions in which the currently prevailing attribute value is saved, and (3) if it becomes necessary to restore an attribute value to the value that prevailed prior to the modification, executing processing for setting the attribute value that has been saved.
In accordance with conventional network management described above, the number of times transmissions and responses are made between the network management system 21 and the network element management systems 11, 12 increases. Moreover, pre-processing for rollback is required. Consequently, a problem which arises is lengthening of response time for responding to the service management system 31 and user terminal 22.
Further, the program for the network management system 21 is not always defined so as to abort execution of the functions possessed by the managed objects. In order to accomplish this, more complicated program logic would be required.